hrm, definately change out the plugs after a seafoam. 98's have plug wires correct(as 99+ get Coil on Plug), so id check those as well.
ive always found stumble/hesitation to be caused by igntion/timing, rather than a fuel problem.
1998 Eclipse GST Spyder - 14b turbo | 3" Catback | Evo8 BoV | 170fwhp if that
2003 Redfire Cobra - 448whp/435wtq - Sold